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Date: Mon, 9 Jul 2018 19:19:00 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 2/6] netfilter: nf_tproxy: fix possible non-linear access to transport header
From: Máté Eckl <ecklm94@...il.com>
This patch fixes a silent out-of-bound read possibility that was present
because of the misuse of this function.
Mostly it was called with a struct udphdr *hp which had only the udphdr
part linearized by the skb_header_pointer, however
nf_tproxy_get_sock_v{4,6} uses it as a tcphdr pointer, so some reads for
tcp specific attributes may be invalid.
Fixes: a583636a83ea ("inet: refactor inet[6]_lookup functions to take skb")
Signed-off-by: Máté Eckl <ecklm94@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/netfilter/nf_tproxy.h | 4 ++--
net/ipv4/netfilter/nf_tproxy_ipv4.c | 18 ++++++++++++------
net/ipv6/netfilter/nf_tproxy_ipv6.c | 18 ++++++++++++------
net/netfilter/xt_TPROXY.c | 8 ++++----
4 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/include/net/netfilter/nf_tproxy.h b/include/net/netfilter/nf_tproxy.h
index 9754a50ecde9..4cc64c8446eb 100644
--- a/include/net/netfilter/nf_tproxy.h
+++ b/include/net/netfilter/nf_tproxy.h
@@ -64,7 +64,7 @@ nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
* belonging to established connections going through that one.
*/
struct sock *
-nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
+nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
@@ -103,7 +103,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
struct sock *sk);
struct sock *
-nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
+nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
diff --git a/net/ipv4/netfilter/nf_tproxy_ipv4.c b/net/ipv4/netfilter/nf_tproxy_ipv4.c
index 805e83ec3ad9..164714104965 100644
--- a/net/ipv4/netfilter/nf_tproxy_ipv4.c
+++ b/net/ipv4/netfilter/nf_tproxy_ipv4.c
@@ -37,7 +37,7 @@ nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
* to a listener socket if there's one */
struct sock *sk2;
- sk2 = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
+ sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, laddr ? laddr : iph->daddr,
hp->source, lport ? lport : hp->dest,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
@@ -71,7 +71,7 @@ __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);
struct sock *
-nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
+nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
@@ -79,16 +79,21 @@ nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
- struct tcphdr *tcph;
switch (protocol) {
- case IPPROTO_TCP:
+ case IPPROTO_TCP: {
+ struct tcphdr _hdr, *hp;
+
+ hp = skb_header_pointer(skb, ip_hdrlen(skb),
+ sizeof(struct tcphdr), &_hdr);
+ if (hp == NULL)
+ return NULL;
+
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
- tcph = hp;
sk = inet_lookup_listener(net, &tcp_hashinfo, skb,
ip_hdrlen(skb) +
- __tcp_hdrlen(tcph),
+ __tcp_hdrlen(hp),
saddr, sport,
daddr, dport,
in->ifindex, 0);
@@ -110,6 +115,7 @@ nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp,
BUG();
}
break;
+ }
case IPPROTO_UDP:
sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
diff --git a/net/ipv6/netfilter/nf_tproxy_ipv6.c b/net/ipv6/netfilter/nf_tproxy_ipv6.c
index bf1d6c421e3b..5dfd33af6451 100644
--- a/net/ipv6/netfilter/nf_tproxy_ipv6.c
+++ b/net/ipv6/netfilter/nf_tproxy_ipv6.c
@@ -55,7 +55,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
* to a listener socket if there's one */
struct sock *sk2;
- sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, hp, tproto,
+ sk2 = nf_tproxy_get_sock_v6(net, skb, thoff, tproto,
&iph->saddr,
nf_tproxy_laddr6(skb, laddr, &iph->daddr),
hp->source,
@@ -72,7 +72,7 @@ nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait6);
struct sock *
-nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
+nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
@@ -80,15 +80,20 @@ nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
const enum nf_tproxy_lookup_t lookup_type)
{
struct sock *sk;
- struct tcphdr *tcph;
switch (protocol) {
- case IPPROTO_TCP:
+ case IPPROTO_TCP: {
+ struct tcphdr _hdr, *hp;
+
+ hp = skb_header_pointer(skb, thoff,
+ sizeof(struct tcphdr), &_hdr);
+ if (hp == NULL)
+ return NULL;
+
switch (lookup_type) {
case NF_TPROXY_LOOKUP_LISTENER:
- tcph = hp;
sk = inet6_lookup_listener(net, &tcp_hashinfo, skb,
- thoff + __tcp_hdrlen(tcph),
+ thoff + __tcp_hdrlen(hp),
saddr, sport,
daddr, ntohs(dport),
in->ifindex, 0);
@@ -110,6 +115,7 @@ nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff, void *hp,
BUG();
}
break;
+ }
case IPPROTO_UDP:
sk = udp6_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 58fce4e749a9..d76550a8b642 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -61,7 +61,7 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
* addresses, this happens if the redirect already happened
* and the current packet belongs to an already established
* connection */
- sk = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
+ sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, iph->daddr,
hp->source, hp->dest,
skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED);
@@ -77,7 +77,7 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
else if (!sk)
/* no, there's no established connection, check if
* there's a listener on the redirected addr/port */
- sk = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol,
+ sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol,
iph->saddr, laddr,
hp->source, lport,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
@@ -150,7 +150,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
* addresses, this happens if the redirect already happened
* and the current packet belongs to an already established
* connection */
- sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, hp, tproto,
+ sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, tproto,
&iph->saddr, &iph->daddr,
hp->source, hp->dest,
xt_in(par), NF_TPROXY_LOOKUP_ESTABLISHED);
@@ -171,7 +171,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
else if (!sk)
/* no there's no established connection, check if
* there's a listener on the redirected addr/port */
- sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, hp,
+ sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff,
tproto, &iph->saddr, laddr,
hp->source, lport,
xt_in(par), NF_TPROXY_LOOKUP_LISTENER);
--
2.11.0
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